1. Field of the Invention
The present invention relates generally to image display devices, and more particularly, to methods and apparatus for displaying both digital images and images produced on transparent support materials intended to be viewed by transillumination.
2. Description of Related Art
In the medical industry, it is well known to use various types of imaging modalities to produce diagnostic images of structures and tissues contained within the body, such as x-ray, Magnetic Resonance Imaging (MRI), Computer Aided Tomography (CAT), ultrasound, etc. X-ray xe2x80x9chardcopyxe2x80x9d images have been the traditional media used for image storage and recording. These hardcopy images are viewed by transillumination, using some form of rear-projected lighting that passes through a light-diffusing surface upon which the hardcopy image rests. The same process of transillumination is also used for other hardcopy image applications, such as in the graphic arts and printing industries. These transillumination viewing devices are often referred to as xe2x80x9cviewboxesxe2x80x9d or xe2x80x9cilluminatorsxe2x80x9d. The light-diffusing surface of the viewboxes can be masked around the peripheral edges of a hardcopy image in order to block the light. It has been shown that xe2x80x9cmaskingxe2x80x9d the surrounding light so that it no longer hits the reader""s eyes improves the reader""s ability to distinguish fainter features on the hardcopy image, and therefore improves the reader""s ability to make accurate diagnoses.
Newer imaging modalities, such as CAT, MRI and ultrasound, generate digital images that are provided to a digital workstation for display on a computer monitor. Similarly, in telemedicine, and specifically teleradiology, hardcopy images can be converted to their digital equivalent through the use of a scanning device for the purpose of transmitting the image to another site for evaluation. The digital workstations may include one or more separate monitors that can be individually controlled to manipulate and adjust the diagnostic image being displayed.
A drawback of the digital workstations is that they currently have no ability to view hardcopy images. Typical digital workstation display devices include some form of cathode ray tube that does not produce enough luminance to properly transilluminate a hardcopy image. Similarly, traditional viewboxes currently have no ability to display digital information. Although digital imaging is a small segment of the current market for image evaluation, it is clear that the market is in transition from hardcopy images to digital images. Nevertheless, it is unlikely that digital imaging will completely supplant hardcopy viewing in the foreseeable future. Perhaps more importantly, as in the case of transition from hardcopy to digital medical images, it will be necessary to review historical hardcopy images with current digital images in close proximity to each other.
It is therefore necessary that a medical facility have available separate and independent display devices.
Accordingly, it would be very desirable to provide a single display device that would permit display of both hardcopy and digital images. It would also be desirable to provide a display device that uses the same working surface to display either or both of these types of images. Moreover, it would be further desirable to provide a method to retrofit current viewboxes to also be able to display digital images and retrofit current display stations to also be able to display hard copy images.
The present invention overcomes the drawbacks of conventional image viewing systems by permitting both hardcopy and digital viewing in the same device.
In an embodiment of the invention, an image viewing station comprises a housing having an internal light source and a light transmissive display panel coupled to the housing such that light from the internal light source passes therethrough. Hardcopy images affixed to an outer surface of the display panel may be transilluminated by the light passing through the display panel. Digital images may also be displayed on the display panel, by projecting the digital images onto either the inner or outer surface of the display panel. The display panel may be selectively masked during hardcopy image viewing, and may further include sensors to detect presence, as well as size and position, of hardcopy images affixed to the display panel.
In another embodiment of the invention, an image viewing station comprises a light emitting or light transmissive display panel, such as a liquid crystal display or an electroluminescent panel. Light emitted by the display panel may be sufficient to transilluminate a hardcopy image disposed on an outer surface of the display panel. A digital image is displayed on the same display panel by selectively driving the pixels of the display panel with digital image data. Alternatively, an internal light source may be included for transillumination of the hardcopy image or for improving backlighting of the digital images. As in the first embodiment, the display panel can be selectively masked around the hardcopy image, and can include sensors to detect presence, size and position of hardcopy images affixed thereto.
The benefits of this invention are numerous and varied. First, as envisioned, for very little additional cost a xe2x80x9cmaskedxe2x80x9d transillumination element could be added to a digital display device. Second, by allowing both hardcopy and digital images to be simultaneously displayed in the same device, a diagnostician can perform comparison studies of differing modalities easily and in close proximity. Third, a combined device will eliminate the need to support dual systems with their attendant additional service and support cost, will free up valuable and scarce physical space, and eliminate the need for duplicate lighting, masking and control elements.
A more complete understanding of the display device for both hardcopy and digital images will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.